A stent is a tubular support structure that may be implanted within a blood vessel or other body vessel to treat blockages, occlusions, narrowing ailments and other related problems that restrict flow through the vessel. When delivered to the site of a constricted vessel and expanded from a compressed configuration to an expanded configuration, the stent exerts a radial force on the vessel wall and prevents it from closing. Balloon-expandable stents expand in response to the inflation of a balloon, whereas self-expanding stents may deploy automatically when released from a delivery device. Self-expanding stents are often fabricated from superelastic or shape memory alloys that can “remember” and recover a previous shape.
In order to effectively treat blockages, occlusions and other ailments that restrict flow through a body vessel, it is important that the stent be precisely placed at the site of the constriction. One approach to achieve precise stent placement is to attach one or more radiopaque markers to the stent to permit visualization of the stent from outside the body using x-ray fluoroscopy. During the implantation procedure, the position of the markers—and thus the position of the stent—may be monitored using a fluoroscope. The x-ray visibility of stents made of metals such as nickel and titanium may be substantially improved by using markers formed from heavier metals such as platinum or gold, which produce higher x-ray contrast. Radiopaque markers may also be beneficial for improving the x-ray visibility of medical devices other than stents.